The present invention relates to the interconversion of crystalline forms of N,N'-ethylene bis-stearamide (EBS).
The crystalline structure of fatty acids has been described by K. S. Markley, Fatty Acids--Their Chemistry, Properties, Production and Uses, Part 4, Chapter XXII, and Part 1, Chapter IV, Interscience Publishers, 1967. Associated thermal properties of fatty acids have been reported also by Markley.
The crystalline state of long chain acid amides and the changes which occur on heating have been studied to a limited degree by J. D. Turner, Univ. Microfilms, Publ. No. 7205, Ann Arbor, Mich., and J. D. Turner and E. C. Lingafelter, Acta. Cryst. 8 549-50 (1955); Chem. Abst. 49, 15352. Single-crystal x-ray studies of even carbon number fatty acid amides from C.sub.10 to C.sub.28 showed three phases, all stable at room temperature. Irreversible changes were reported by T. Sakurai, J. Phys. Soc. Japan 10, 1040-8 (1955); Chemical Abstracts 50, 6125. Comparison of iso acids, explanations for the physical configuration of the crystalline states and differences in the numbers of states have been investigated (See K. E. Arosenius, et al, Arkiv Kemi, Mineral Geol. 26A No. 19-20 (1048); Chem. Abst. 44, 3883, and S. Kurokawa, Bull. Chem. Soc. Japan 28, 660-4 (1955); Chem. Abst. 50, 6868) along with some correlative exploration of the infrared differences found for different molecular orientations (See P. A. Chollet, et al, Report 1975, CEA-N-1814. ERDA Energy Res. Abstr. 1976, 1(6); Chem. Abst. 86, 29112; and K. Machida, Spectrochim. Acta, Part A 1972, 28(2), 235-56; Chem. Abst. 70, 78705X). These sources, as cited in Chemical Abstracts do not describe studies of fatty acid long chain diamides in respect to crystalline structure and associated thermal or spectral relationships.
Bis-amides of fatty acids are known to be useful lubricants and in the production of polymeric materials such as polyvinyl chloride. These bis-amides are particularly useful in the preparation of defoamer compositions as described in U.S. Pat. Nos. 3,652,453; 3,673,105; 3,677,963; 3,935,121; 3,951,853; 3,990,905; 4,032,473; and 4,088,601. A preferred bis-amide for such applications is N,N'-ethylene bis-stearamide.
Unfortunately, the use of bis-amides as noted above has not been entirely trouble free. For example, one of the major concerns in the preparation and use of defoamer compositions is to provide an efficient defoamer which does not gel prior to use.
We have found that there is a need in paper defoamer use, some plastic applications and preparation of lubricants for essentially pure compositions of EBS and other bis-amides of a single discrete crystalline form or mixtures thereof. Prior to the present invention, the art has failed to provide a means for the preparation of crystalline forms of EBS in a controlled fashion suitable for large scale production.
Accordingly, it is the primary object of the present invention to provide a process for the production of N,N'-ethylene bis-stearamide in pure crystalline forms or mixtures thereof.
It is a further object of the present invention to provide a controlled means for large scale production of EBS in desired crystalline forms.
These and other objects of the invention will become more apparent from the discussion which follows.